Defending Aotearoa New Zealand’s plant systems from invasive species – value, impact, investment and benefit

HIGHLIGHTS: Invasive alien species are increasingly recognised for their negative impact on economic, environmental, social and cultural assets and values throughout the world, including Aotearoa New Zealand. Here we briefly describe New Zealand’s biosecurity system, and place this in the context of the many challenges it faces in an ever-changing world. This paper then summarises and assesses information on the magnitude of the biosecurity challenge for New Zealand’s plant systems in terms of: (1) assets to be protected; (2) current impacts from invasive species found in New Zealand; (3) potential impacts from invasive species not yet found in New Zealand; (4) investment in defensive biosecurity activities; and (5) attempts to determine the return on investment for biosecurity operations and research. Our findings indicate that the economic impacts of established invasive species and potential impacts from non-established invasive species are in the billions of dollars, and that there are sizable benefit-cost ratios for investment in mitigating these impacts, including investment in research. This information can inform policy development and provide the basis for developing an economic or value framework for investment in biosecurity, and especially for plant border biosecurity.